You will recognize this as Learn's "ActiveRecord Validations Lab" with two added tests. We are going to refactor its test files to use factories, and be more explicit about what is getting tested (by removing let).

First, use valid attributes to create Post and Author factories. There will be no need to invoke Model#new in any of your tests. Rely on building and createing your factory blueprints.

Next, remove all the let declarations by moving logic directly into the test examples. Here is an example from the post_spec.rb.

BEFORE (as it stands now):

it "is invalid with too short content" do
  expect(short_content).to be_invalid
end

AFTER you fix it:

it "is invalid with too short content" do
  expect(build(:post, content: "too short")).to be_invalid
end